This invention relates to methods and apparatus for sampling liquids under conditions that maximize precise analysis of ingredients.
In one class of methods and apparatuses for sampling liquids, the apparatus automatically draws samples of known amounts of liquids at preprogrammed intervals and deposits them into containers, which are usually bottles. The prior art automatic samplers of this class fill open containers. This type of automatic sampler has a disadvantage if used to sample liquids with volatile materials in them because substantial amounts of the volatile materials escape before measurement.
Another class of sampler includes containers that can be opened to receive liquid and closed after filling without air space within them to preserve as much of the volatile materials that are within the liquid before being drawn as possible. A prior art type of sampler of this class includes a valve in an inlet conduit and a valve in an outlet conduit. This type of valve has a disadvantage in that it is difficult to automate because of the number and types of valves, the size of the valves and the size of the plumbing associated with the valves. A system of this type is disclosed in U.S. Pat. Nos. 4,974,456 and 4,864,877.
Bladder pumps are known for drawing samples. However, bladder pumps have not been connected to automatic sample collectors to collect samples automatically. In the prior art, peristaltic pumps have been used with automatic samplers, probably because of their ability to pump with shallow liquid depth and because of the simplicity and economy that results from being driven by an electrical motor rather than compressed air as in the case of bladder pumps.